The present invention relates to a class of novel chiral compounds, a process for the preparation thereof, the use thereof as catalysts, and a process for mediating asymmetric organic transformations therewith. More specifically, the invention relates to a novel class of atropisomeric analogues of 4-aminopyridine, the preparation thereof, the use thereof as catalysts, and a method for performing enantioselective acylation (and related transformations) using the catalyst to preferentially mediate reaction of one enantiomer of an enantiomer pair in a racemic mixture by means of simple-(e.g. H. B. Kagan et al. Top. Stereochem. 1988, 18, 249), parallel-(e.g. E. Vedejs et al. J. Am. Chem. Soc. 1997, 119, 2584), or dynamic-(e.g. S. Caddick et al. Chem. Soc. Rev. 1996, 25, 447) kinetic resolution; or preferentially mediate reaction of one of two enantiotopic functional groups in an achiral meso compound by means of enantioselective desymmetrisation (e.g. M. C. Willis, J. Chem. Soc., Perkin Trans. 1 1999, 1765).
Kinetic resolution relies on the fact that one enantiomer of an enantiomer pair in a racemic mixture will react at a faster rate with an enantiomerically enriched chiral reagent or in the presence of an enantiomerically enriched chiral catalyst than the other. Enantioselective desymmetrisation relies on the fact that one of two enantiotopic functional groups in an achiral meso compound will react at a faster rate with an enantiomerically enriched chiral reagent or in the presence of an enantiomerically enriched chiral catalyst than the other.
Enantiomerically enriched reagents and catalysts have enormous potential for the efficient synthesis of enantiomerically highly enriched products such as pharmaceuticals, agrochemicals, fragrances and flavourings, conducting and light emitting polymers and the like. The use of such products in enantiomerically highly enriched form, and preferably as single enantiomers, is significant both for performance reasons and also in some cases to comply with regulatory constraints. Such constraints apply particularly to compounds intended for human or animal consumption or application wherein the desired enantiomer is active and its antipode may be either inert or harmful.
Enantioselective acylation by means of kinetic resolution or enantioselective desymmetrisation is traditionally performed using enzymes. High selectivities (E: 7-1000, wherein E is enzymatic enantioselectivity) have been obtained for selected substrates with specific enzymes (e.g. S. M. Roberts J. Chem. Soc., Perkin Trans. 1 1998, 157). However, those enzymes which are compatible with the widest range of substrates (e.g. lipases) are often of low selectivity. Moreover, lipase-mediated acylations can be reversible and undesired equilibria can cause problems. Additionally, enzymes are provided by nature in only one enantiomeric form and are invariably both thermally and mechanically unstable. Furthermore their reactions are usually heterogeneous, only operate efficiently within narrow reaction parameters, are prone to inhibition phenomena, display poor batch-to-batch reproducibility, and consequently are difficult to scale-up.
Recently, chemical methods for mediating enantioselective acylation by means of kinetic resolution or enantioselective desymmetrisation have begun to emerge. Early methods relied on the use of enantiomerically enriched chiral acylating reagents (e.g. D. A. Evans et al. Tetrahedron Lett. 1993, 34, 5563) but promising chiral chemical catalysts are now being developed. Chiral chemical catalysts offer some attractive features relative to the use of enzymes. Reactions catalysed in this manner can be rendered irreversible such that no undesired equilibria are present. Chemical catalysts can be made in both enantiomeric forms. Chemical catalysts can be thermally and physically robust. Chemical catalysts can be used under homogeneous conditions. Ideally, they can constitute a tiny fraction of the material to be processed, and can be readily recovered.
The stereoselectivity factor s is the counterpart to enzymatic enantioselectivity, E. Kagan""s equation for s for the kinetic resolution of a given substrate (e.g. a secondary alcohol) reacting by pseudo-first order kinetics is given by:                     p        ⁢        r            ⁢              xe2x80x83            ⁢      o      ⁢              xe2x80x83            ⁢      d      ⁢              xe2x80x83            ⁢      u      ⁢              xe2x80x83            ⁢      c      ⁢              xe2x80x83            ⁢              t        :        s              =                  ln        ⁡                  [                      1            -                          C              ⁢                              (                                  1                  +                                      e                    ⁢                                          xe2x80x83                                        ⁢                                          e                      xe2x80x2                                                                      )                                              ]                            ln        ⁡                  [                      1            -                          C              ⁢                              (                                  1                  -                                      e                    ⁢                                          xe2x80x83                                        ⁢                                          e                      xe2x80x2                                                                      )                                              ]                                r      ⁢              xe2x80x83            ⁢      e      ⁢              xe2x80x83            ⁢      c      ⁢              xe2x80x83            ⁢      o      ⁢              xe2x80x83            ⁢      v      ⁢              xe2x80x83            ⁢      e      ⁢              xe2x80x83            ⁢      r      ⁢              xe2x80x83            ⁢      e      ⁢              xe2x80x83            ⁢      d      ⁢              xe2x80x83            ⁢      s      ⁢              xe2x80x83            ⁢      t      ⁢              xe2x80x83            ⁢      a      ⁢              xe2x80x83            ⁢      r      ⁢              xe2x80x83            ⁢      t      ⁢              xe2x80x83            ⁢      in      ⁢              xe2x80x83            ⁢      g      ⁢              xe2x80x83            ⁢      m      ⁢              xe2x80x83            ⁢      a      ⁢              xe2x80x83            ⁢      t      ⁢              xe2x80x83            ⁢      e      ⁢              xe2x80x83            ⁢      r      ⁢              xe2x80x83            ⁢      i      ⁢              xe2x80x83            ⁢      a      ⁢              xe2x80x83            ⁢              l        :        s              =                  ln        ⁡                  [                                    (                              1                -                C                            )                        ⁢                          (                              1                -                                  e                  ⁢                                      xe2x80x83                                    ⁢                  e                                            )                                ]                            ln        ⁡                  [                                    (                              1                -                C                            )                        ⁢                          (                              1                +                                  e                  ⁢                                      xe2x80x83                                    ⁢                  e                                            )                                ]                    
where C is the conversion (as a fraction of unity, sum of both reaction enantiomers) while ee and eexe2x80x2 are the enantiomeric excess values of unreacted alcohol and the product, respectively. The enantiomeric excess ee is also referred to as the optical purity; cc is the proportion of (major enantiomer)xe2x80x94(minor enantiomer). For example, a 90% optical purity is 90% ee, i.e., the enantiomer ratio is 95:5, major:minor. Using as an example acylation of a secondary alcohol via kinetic resolution, if s=50, the eexe2x80x2 value of the chiral ester product of kinetic resolution remains above 90% until the conversion exceeds 46%. For example, the unreacted (chiral) alcohol reaches 80% ee at 50% conversion (C=0.5) and 99% ee at 55% conversion. Theoretically, the less reactive alcohol enintiomer could therefore be recovered with 90% efficiency and 99% ee (45% yield based on racemic alcohol).
Impressive selectivities (s: 7-400) have been reported for a number of enantioselective acylation processes by means of kinetic resolution or enantioselective desymmetrisation using a variety of chiral chemical catalysts. Such chiral chemical catalysts are chiral Lewis acids (e.g. F. Iwasaki Org. Letts. 1999, 1, 969), chiral phosphines (e.g. E. Vedejs et al. J. Am. Chem. Soc. 1999, 121, 5813), chiral diamines (e.g. T. Oriyama et al. Chem. Lett. 1999, 265), chiral imidazoles (e.g. S. J. Miller et al. J. Org. Chem. 1998, 63, 6784), and chiral 4-aminopyridines (e.g. E. Vedejs et al. J. Am. Chem. Soc. 1997, 119, 2584; G. C. Fu et al. J. Am. Chem. Soc. 1999, 121, 5091; G. C. Fu et al. J. Org. Chem. 1998, 63, 2794; K. Fuji et al. J. Am. Chem. Soc. 1997, 119, 3169). All these chiral chemical catalysts except the chiral Lewis acids are believed to operate by nucleophilic catalysis. A possible mechanism of nucleophilic catalysis of acylation of a secondary alcohol mediated by the achiral 4-aminopyridine derivative 4-dimethylaminopyridine (DMAP) is illustrated in Scheme A. 
Of the chiral 4-aminopyridine-based catalysts, Fu""s planar chiral ferrocenyl chiral 4-aminopyrindine has been shown to be the most versatile (e.g. G. C. Fu et al. J. Org. Chem. 1998, 63, 2794). It catalyses a variety of useful enantioselective acylation processes by means of kinetic resolution (e.g. of arylalkylcarbinols with acetic anhydride) via nucleophilic catalysis with excellent selectivity (s: 7-100). However, the published synthesis involves 13 linear steps, has an overall yield of 0.6% from adiponitrile (for the racemate), requires glove-box techniques, and involves chiral stationary phase high-performance liquid chromatography (HPLC) for the final enantiomer separation. Additionally, it is a slow catalyst, typically requiring several days at 0xc2x0 C. in tert-amyl alcohol to give efficient resolution.
Accordingly, there is a need for enantioselective catalysts which are capable of mediating enantioselective acylation with high selectivity, which can be readily synthesised in high yield and used in low quantities, and which are readily recovered.
We have now found a novel class of catalysts that meet some or all of these needs, specifically provide comparable selectivity, are faster catalysts and are readily prepared, and moreover provide a number of additional advantages. Specifically we have developed a conceptually new class of nucleophilic chiral 4-aminopyridine molecules as catalysts. These molecules possess axial asymmetry as the result of restricted rotation about a highly hindered sp2-sp2 biaryl axis.
In the broadest aspect of the invention there is provided a chiral catalyst comprising a 3,4-disubstituted pyridine, or a salt, N-functionalised derivative, dimer or oligomer thereof, wherein the 3-substituent is substantially hindered from rotation about the bond (sp2-sp2 biaryl axis) linking it to pyridine and the 4-substituent is an aliphatic or aromatic amine linked by a single bond to the pyridine, the pyridine nitrogen being functionalised or unfunctionalised. The catalyst may be provided as its racemic mixture or as only one of its atropisomers.
It is a particular advantage of the invention that the compounds are readily synthesised and resolved. The catalyst is highly active and catalyses rapid reaction.
We have found that with appropriate substitution the atropisomers of the pyridine derivatives of the invention are highly resistant to rotation about the bond at the 3-position, rendering the atropisomers highly resistant to racemisation.
Accordingly, in a first aspect of the invention there is provided a catalyst comprising a compound of formula I: 
wherein Z is a group substantially hindered from rotation about its bond; and
each of R1 and R2 are independently selected from C1-30 alkyl, C3-30 cyclo alkyl and/or C3-30 aryl, or NR1 R2 form a cyclic amine; wherein R1 and/or R2 may be optionally substituted and/or include one or more heteroatoms; or
a salt, N-functionalised derivative, dimer or oligomer thereof.
Preferably the pyridine 5-substituent is hydrogen.
A class of 4, 5-(fused) substituted compounds is disclosed in A. C. Spivey et al. Tetrahedron Lett. 1998, 38, 8919, which studied rates of catalysis. We have now however found that 5-position substitution is detrimental to the efficiency of compounds as asymmetric catalysts, in contrast to the class of compounds of the invention.
More preferably the invention relates to a catalyst comprising a compund of formula II: 
wherein R1 and R2 are as hereinbefore defined;
R3 is selected from C1-20 alkyl, C3-20 cyclo alkyl and/or C3-20 aryl, wherein R3 may be optionally substituted and/or include one or more hetero atoms; and
R4 is C1-20 alkyl, C3-20 cyclo alkyl and/or C3-20 aryl or R4 and R5 together are a C3-20 fused cyclic or aromatic group wherein R4 or R4 and R5 together may be optionally substituted or include one or more hetero atoms; or
a salt, N-functionalised derivative, dimer or oligomer thereof.
The compounds of formulae I or II as hereinbefore defined may be further substituted or unsubstituted in the pyridine 2- and/or 6-positions and/or in the Z ring. Substituents are independently selected from one or more R6, wherein R6 is selected from for example C1-20 alkyl or C3-20 aryl, either being optionally substituted or including one or more heteroatoms.
Preferably each of R1 and R2 and R3 independently are selected from: straight or branched chain lower (C1-5) or higher (C6-20) alkyl, more preferably methyl, ethyl, propyl, butyl, pentyl or hexyl, heptyl, octyl; or from C3-20 cyclo alkyl, preferably C3-C14 cyclo alkyl; or from C6-24 aryl, more preferably an unfused, optionally Spiro 1, 2, 3, 4 or 5 ring alkyl or aryl structure; any of which are optionally substituted and/or include at least one heteroatom; or
R1 and R2 together form an optionally substituted cyclo amine, such as 
wherein m=1-8 and each Y is independently selected from (CH2)nYxe2x80x2p 
wherein n=1-8, p=0-4 and the sum of n and p is at least 2, and each Yxe2x80x2 is independently selected from NR7, O, S, P or Si,
preferably Y is (CH2)nxe2x80x2Yxe2x80x2 wherein nxe2x80x2 is 1-3 or the cyclic amine is 
wherein R7 is as hereinbefore defined for R1 or forms a dimer or oligomer of a moiety of compound of formula I: 
or R3 comprises optionally substituted phenyl or biphenyl, such as optionally substituted (3,5-diphenyl)phenyl, such as [(3xe2x80x2,3xe2x80x3,5xe2x80x2,5xe2x80x3-tetramethyl)-3,5-diphenyl]phenyl.
Preferably the catalyst as hereinbefore defined is a compound of formula III: 
wherein R1-R3 and R6 are as hereinbefore defined; or a salt, N-functionalised derivative, dimer or oligomer thereof.
Any optional substituents or R6 as hereinbefore defined may be independently selected from any groups that improve or do not detract from performance of the compounds as catalyst.
Suitable substituents include halide, hydroxy, amino, alkoxy, alkyl, cycloalkyl aryl, such as hereinbefore preferably defined for R1, R2 or R3.
Heteroatoms as hereinbefore defined include optionally substituted N, O, S, P, Si.
More preferably, the catalyst as hereinbefore defined is a compound of formula III in which: R1 and R2 are methyl, ethyl, propyl, or butyl; or R1 and R2 together form a pyrrolidinyl-, piperidinyl-, or morpholinyl ring; and R3 comprises a phenyl, 4xe2x80x2-biphenyl, (3,5-diphenyl)phenyl, or [(3xe2x80x2,3xe2x80x3,5xe2x80x2,5xe2x80x3-tetramethyl)-3,5-diphenyl]phenyl.
Without being limited to this theory it is thought that the compounds of the invention may be rationally designed with respect to the atropisomeric moiety by selection of the group preventing rotation about the pyridine 3-bond, the active catalytic moiety by selection of the amine substituents, and the transformation selective moiety by variation at the pyridine N. Without varying the pyridine N the catalyst is effective for acylation reactions and other transformations for which the high nucleophilicity of this moiety elicits catalytic behaviour whilst the formation of various salts and N-dipolar adducts, for example N-oxide and N-borane adducts, will affect the reactive nature of the N and provide access to other transformations.
In a further aspect of the invention there is provided a composition or a support comprising a catalytically effective amount of a catalyst as hereinbefore defined together with suitable solvent, dilutent and the like or together with a suitable linker on a macromolecule, polymer or a solid support. A supported catalyst may be useful in combinatorial chemistry for conducting plural parallel reaction with labelling and identification of reaction products thereby negating the need for analysis.
In a further aspect of the invention there is provided a compound or formula I, II or III as hereinbefore defined.
In a further aspect of the invention there is provided a process for the preparation of a compound of formula I, II or III as hereinbefore defined comprising cross-coupling a compound of formula IV with an organometal derivative R3xe2x80x94M (Scheme B). 
Wherein each R6 independently is hydrogen or is defined as hereinabove, and R1, R2, R3, R4, and R5 are defined as hereinabove and wherein X is a group which is such that palladium or nickel or a similar transition metal can be oxidatively inserted into the bond between X and the adjacent aryl carbon atom. M is Li, Mg, Zn, Hg, Ti, Al, Zr, Tl, Sn, B and mixtures thereof or a derivative, salt or xe2x80x9catexe2x80x9d complex thereof.
Preferably, X is a halide, sulfonate, for example trifloxy (OTf), or diazonium salt.
Preferably, the cross-coupling is catalysed by palladium(0) or nickel(0). Preferably, M=MgX, SnR3, or B(OR)2 (i.e. the Kharasch, Stille, and Suzuki cross-coupling protocols respectively, e.g. S. P. Stanforth, Tetrahedron 1998, 64, 263).
For example, intermediate IV wherein X=OTf is cross-coupled with an appropriate organo-Grignard derivative (R3xe2x80x94MgBr) in the presence of a catalytic quantity of palladium(0) in a Kharasch-type process.
The product is obtained as a racemic mixture and may subsequently be separated by methods as known in the art, such as by chiral stationary phase HPLC as previously disclosed (A. C. Spivey et al. Tetrahedron Lett. 1998, 39, 8919), or preferably by atropisomer-selective transformation with salt formation, enabling resolution. Preferably suitable salt-forming agents are identified by parallel screening as disclosed in xe2x80x9cApplication of Automation and Thermal Analysis to Resolving Agent Selectionxe2x80x9d, M. B. Mitchell et al. Org. Proc. Res. Dev. 1999, 3, 161, using suitable selection of chiral acids in solution of solvents such as ethanol or less polar solvents such as ethyl acetate.
More preferably separation is by atropisomer-selective salt formation using a commercially available chiral acid: (S)-N-tert-butoxycarbonyl-O-benzyl-tyrosine in isopropanol.
Alternatively, the product may be obtained directly from the cross-coupling reaction as a non-racemic mixture by incorporating chiral ligands in the coupling procedure (cf. S. L. Buchwald et al. J. Am Chem. Soc. 2000, ASAP web release date 11th November), preferably binapthyl ligands.
In a further aspect of the invention there is provided a process for the preparation of an intermediate of formula IV as hereinbefore defined comprising: cross-coupling with concomitant hydrodehalogenation, of an intermediate 4-aminopyridine derivative of formula VI to an arylmetal V; and, for compounds wherein Xxe2x89xa0Y, subsequent conversion of group Y into group X by methods known in the art (Scheme C). 
Wherein R1 and R2, and R4, R5, and R6 and M are as hereinbefore defined, W is a halide substituent, and Y is as hitherto defined for X or a substituent of the form OR wherein R is a substituent, known in the art as a protecting group, which allows for conversion to the corresponding compound wherein Y=X by methods known in the art to the corresponding compound wherein Yxe2x95x90OH which is readily converted by methods known in the art to a substituent hitherto defined as X.
Preferably, W is a bromide and Y is a substituent of the form OR wherein R is a protecting group which allows for conversion by hydrogenolysis, as known in the art, to the corresponding phenol wherein Yxe2x95x90OH [e.g. benzyloxy (OBn), or substituted benzyloxy] and transformation of this phenol to an aryl sulfonate (e.g. triflate) suitable for cross-coupling is by methods known in the art (e.g. by reaction with an appropriate sulfonic anhydride, -fluoride or -chloride).
Preferably, the cross-coupling is catalysed by palladium(0). Preferably, M=B(OR)2 (i.e. a Suzuki cross-coupling protocol, e.g. N. Miyaura et al. Synth. Commun. 1981, 11, 513) which, under appropriate conditions as known in the art, also effects hydrodehalogenation of the 5-halogen substituent.
For example, intermediate VI wherein W=Br and R1=R2=Et is cross-coupled with an appropriate boronic acid derivative V wherein Y=OBn, and M=B(OH)2 in the presence of a catalytic quantity of palladiiim(0) in a Suzuki-type process with concomitant 5-hydrodebromination to give, after transformation of Y=OBn to Y=OTf by known methods, intermediate IV.
Utilisation of cross-coupling of 3-halogen-substituted DMAP derivatives with appropriate organo-metal derivatives by analogy to a method previously disclosed (A. C. Spivey et al. Tetrahedron Lett. 1998, 38, 8919) can be used to access compounds of structure IV (A. C. Spivey et al. J Org. Chem. 2000, 65, 3154) but this normally high-yielding process gave very poor yields for the class of analogues of the invention (Scheme D). 
Notwithstanding the possibility that this type of cross-coupling could be optimised, we developed the novel process outlined hithertofore (Scheme C).
The compounds are obtained in excellent yield. The process is also suited for preparation of a range of analogues having different substituents, specifically amine and 3-pyridyl substituents.
The aryl boronate coupling partner V can be obtained commercially or by known means from the appropriate aryl halide, for example as shown in Scheme E, by conversion from commercially available 1-bromo-2-naphthol or an analogue thereof (A. C. Spivey et al. J Org. Chem. 2000, 65, 3154). 
The intermediate 4-aminopyridine derivative of formula VI can be obtained according to the process outlined in Scheme F. 
Herein, intermediate 4-aminopyridine derivative of formula VI is obtained from reaction of the trihalopryidine VII with the appropriate secondary amine in the corresponding formamide solvent at elevated temperature. The intermediate trihalopyridine of formula VII is suitably obtained by reaction of the corresponding 3,5-dihalo-4-pyridone of formula VIII with a chlorinating agent. The 3,5-dihalo-4-pyridone of formula VIII is suitably obtained by halogenation of commercially available 4-pyridone.
It is a particular advantage of the invention that the compounds may be prepared simply and conveniently in high yield and conveniently separated into atropisomers illustrated in Scheme G. 
Kinetic parameters were obtained and indicated that an enantiomerically pure sample of suitably highly substituted compounds of the invention would lose much less than 1% of their optical purity over one year in solution at room temperature (A. C. Spivey et al. J. Org. Chem. 2000, 65, 3154).
In a further aspect of the invention there is provided a novel intermediate as hereinbefore defined.
In a further aspect of the invention there is provided a catalyst comprising an enantiomer of a compound or formula I, II, or III as hereinbefore defined.
The catalyst is highly active and catalyses rapid reaction.
In a further aspect of the invention there is provided a process for stereoselective reaction of a catalyst of formula I, II, III as hereinbefore defined with an optically inactive substrate to provide one or both enantiomers of a derivative thereof, with simultaneous or subsequent recovery of the catalyst. The invention includes subsequent separation of the product enantiomers.
The reaction may be any suitable reaction that may be catalysed by the catalyst of the invention, including its salts and N-dipolar adducts.
Preferably the process comprises the enantioselective acylation by means of kinetic resolution of e.g. a secondary or tertiary alcohol or primary or secondary amine for which the acylated or further derivative can be industrially useful in enantiomeric form as a pharmaceutical, agrochemical, fragrance, flavouring or as a constituent of a high-value electrically or optically active polymer or the like.
More preferably, the process comprises the reaction of an alcohol of formula IX, wherein R8 and R9 are independently selected from C1-50 alkyl, C3-50 cyclo alkyl or C3-30 aryl, with an acylating agent R10COU, wherein R10 is optionally substituted C1-15 alkyl or C1-12 aryl and U is an appropriate leaving group, such as anhydride, under acylating conditions, as known in the art, in the presence of a enantiomerically highly enriched catalyst (preferably xe2x89xa790% ee) of formula I, II or III as hereinbefore defined, according to Scheme H. 
Preferably, the catalyst is enantiomerically enriched such that its ee is xe2x89xa798%. More preferably, the catalyst is enantiomerically enriched such that its ee is xe2x89xa799%, more preferably xe2x89xa799.9%.
Suitable choice of acylating agent, temperature, solvent, and stoichiometric base have been found to improve selectivity of reaction.
The transformation is catalysed with high selectivity (s: 7-500). Selectivities in excess of 50 may be obtained by optimisation. The enantiomeric excess of the products (eexe2x80x2) may be improved, as known in the art, by repeat transformation using the opposite enantiomer of catalyst (i.e. double kinetic resolution: e.g. S. M. Brown et al. Tetrahedron: Asymmetry 1991, 2, 511).
Resolution of enantiomers in the process of the invention provides optical purity in excess of 70% preferably in excess of 90% depending on the extent of conversion C.
Alternatively, the process comprises the enantioselective acylation by means of enantioselective desymmetrisation of an achiral meso diol or diamine. The enantioselective reaction of enantiotopic functional groups under acylating conditions in these situations can yield a single enantiomer of the product in yields up to 100%. Additionally, as known in the art, it is usual in such systems that the enantiomeric purity of the monofunctionalised product increases as a function of conversion due to preferential further conversion (i.e. kinetic resolution) of the minor enantiomer into a meso difunctionalised product (i.e. the xe2x80x98meso-trickxe2x80x99: e.g. S. L. Schreiber, et al. J. Am. Chem. Soc. 1987, 109, 1525).
Catalyst recovery is suitably 90-100%. Advantageously, catalytic performance is highly reproducible.
The catalyst of the invention may be used in any suitable form and amount. Catalytic amounts of 0.001 to 2 mol %, preferably 0.01 to 0.2 mol %, more preferably 0.05 to 0.15 mol % may be used.
In a further aspect of the invention there is provided a product of a catalytic reaction obtained with use of a catalyst as hereinbefore defined.
The invention is now illustrated in non-limiting manner with reference to the following examples and figures.